Process for improving the rheological properties of an aqueous dispersion

ABSTRACT

A process for improving the rheological properties of an aqueous dispersion comprising adding a rheology modifier to the aqueous dispersion, and then adding a water soluble synthetic polymer flocculant to the aqueous dispersion. The rheology modifier may be selected from the group consisting of natural polymers, semi-natural polymers, synthetic materials and combinations thereof. The water soluble synthetic polymer flocculant may be selected from the group consisting of water soluble anionic polymers, cationic polymers, amphoteric polymers, nonionic polymers, and combinations thereof.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Patent Application No.61/702,783, filed Sep. 19, 2012. U.S. Patent Application No. 61/702,783is incorporated herein in its entirety by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

Processes for improving the rheological properties of an aqueousdispersion comprising adding an effective amount of a rheology modifierto the aqueous dispersion, typically in combination with a syntheticwater-soluble polymer flocculant. The process is particularly applicableto mining operations.

The Related Art

In the production of valuable metals and minerals in mining, ore bodiesare typically ground, dispersed in aqueous solutions, treated withagents, and subjected to various processing conditions (temperature, pH,pressure, shear rate). The intended result of the mining operation is togenerate aqueous dispersions that will undergo isolation, separation, orpurification of the valuable portion of the ore, whether it is a metalor mineral.

Aqueous dispersions that result from the subject mining operations arecomprised of mixtures of water, solids, and other materials. Examples ofthe types of solids typically found in the aqueous dispersions frommineral operations include minerals, metals, metal oxides, metalsulfides, metal hydroxides, salts, organic matter, and other inorganicmatter. Aqueous dispersions that are comprised of ores, concentrates,tailings and the like, which may contain particles that havemorphologies that are not conducive for rapid sedimentation or pumpingare of particular interest. The pumped concentrated aqueous dispersionsmay contain valuable minerals or metals or waste residues. Valuableresources found in the aqueous dispersions may include minerals(bauxites, latherites, or sulfides), metals (such as iron, base metals,precious metals, light metals, and uranium), coal and the like. Thewaste streams consist of gangue minerals and other constituents withlittle or no value. Typically, aqueous dispersions are processed bytreatment with flocculating or coagulating agents to initiateliquid-solid separation that concentrates the solids portion of theaqueous dispersion in appropriate separation processes, e.g.centrifuging, concentrating, sedimentation, dewatering, filtering andthe like.

Liquid-solid separations facilitated by the use of coagulating and/orflocculating agents are required to further concentrate the aqueousdispersions to reduce the process costs associated with transport,calcination, separation, digestion, or storage. Liquid-solid separationsare now more challenging because ore bodies that are processed todaycontain lower concentrations of the valuable minerals and metals andhigher concentration of gangue minerals. Gangue comprises that portionof ore bodies that is unusable or of low value, and gangue typicallyconsists of fine particles of irregular shape. Liquid-solid separationsare accelerated by the use of synthetic or natural polymers prior totransporting the aqueous dispersion from where it is found or generatedto the facility where it is stored, calcined, separated, or transported.Due to the size and shape of the gangue particles, gangue minerals aremore difficult to agglomerate; therefore, higher dosages of synthetic ornatural polymer flocculants are required to achieve the samesedimentation rates necessary to maintain desired mill flow rates. Whatmakes the transport of the concentrated aqueous dispersions even morechallenging is that the chemicals used to coagulate or flocculate thesolids of the aqueous dispersions promote higher rheological parameters,such as higher viscosity or higher yield stress for the concentratedsolids and make the solids even more difficult to pump.

Use of high molecular weight, synthetic polymer flocculants impartshigher rheological characteristics making pumping of the aqueousdispersions more difficult, as a consequence operating cost andprofitability are negatively impacted. Preferably, concentrated aqueousdispersions should exhibit low yield stresses to allow pumping at lowthreshold energy levels. Additionally, concentrated aqueous dispersionsshould possess low viscosities, which should result in fast flow ratesthrough mining processes for improved efficiency, productivity, andlower energy costs at the mills or refineries. In order for miningcompanies to remain profitable, there is a need for mining operations tobe able to process concentrated aqueous dispersions efficiently byreducing the rheological properties of the substrates.

All parts and percentages set forth herein are on a weight by weightbasis unless otherwise specified. Mw is the weight average molecularweight as determined by SEC-MALLS analysis. MALLS shall mean and referto multi-angular laser light scattering. SEC-MALLS shall mean and referto a size exclusion chromatography technique using MALLS to determineMw.

SUMMARY OF THE INVENTION

The invention pertains to a process for improving the rheologicalproperties of an aqueous dispersion. The process comprises adding aneffective amount of at least one rheology modifier to the aqueousdispersion. Typically, the rheology modifier is added to the aqueoussystem in combination with at least one synthetic water-soluble polymerflocculant, and in this case the rheology modifier is usually addedprior to the flocculant.

The rheology modifier is selected from the group consisting of naturalpolymers, semi-natural polymers, synthetic materials and combinationsthereof. Semi-natural polymers are chemically modified or syntheticallymodified natural polymers. The synthetic materials typically comprisecationic or anionic polymers or monomers.

The process may be applied in mining operations for improving therheological properties of aqueous dispersions, such as mining slurries.For example, the process may be applied for liquid solid separation,such as in a gravity thickener, clarifier and/or hydrocyclone.Typically, the process is useful in operations involving mineralslurries comprising gold, phosphate, silver, platinum, copper, nickel,zinc, lead, molybdenum, iron, coal, aluminum (bauxite) and the like

By using the defined process it was discovered that the yield stress ofthe aqueous dispersion was reduced. The reduction of the yield stress ofthe aqueous dispersion is important because aqueous slurries having alower yield stress can be transported through pipelines and otherequipment more rapidly and efficiently, which results in increasedproductivity and energy savings. In addition, the flocculation,sedimentation, and dewatering processes required for successfulliquid-solid separation are accelerated through application of theprocess.

Yield stress means and refers to the amount of energy required to starta solids moving as measured by vane rheometry. Aspect ratio is definedby the ratio of the minimum to the maximum Feret diameter as measured byx-ray diffraction. The aspect ratio provides an indication of theelongation and sphericity of a particle, where the sphericity of theparticle is inversely proportional to the aspect ratio.

DETAILED DESCRIPTION OF THE INVENTION

Among the natural polymers that can be used in the process arepolysaccharides, such as potato starch, xanthan gums, guars, dextran,cellulose derivatives and glycosaminoglycans. Preferably, the naturalpolymer used in the subject invention comprises dextran. Typically usedas the polysaccharide is a dextran having a Mw of from about 5,000 toabout 40,000,000, preferably from about 50,000 to about 25,000,000 andmore preferably from about 200,000 to about 10,000,000. Typically, thePDI of the polysaccharide is from about 1.0 to about 10.0, moretypically from about 1.1 to about 9.0, and most typically from about 1.2to about 8.0. Persons of ordinary skill in these arts, after readingthis disclosure, will appreciate that all ranges and values within theseexplicitly stated ranges are contemplated. Natural polymers sold underthe trade names ZALTA® VM 1120 and ZALTA® VM 1122, both available fromAshland. Inc., Wilmington, Del. USA (“Ashland”), may be used.

The semi-natural polymers include lignosulfonates, such as calciumlignosulfonate, and chemically modified polysaccharides. Modifiedpolysaccharides typically useful in the process include modifiedstarches, such as cationic starch; modified guar gum, such as cationicguar gum; and modified celluloses such as anionic carboxymethylcellulose and hydroxyethyl cellulose. Combinations of semi-naturalpolymers may be used.

The synthetic material is typically selected from the group consistingof cationic inorganic polymer, cationic inorganic molecule, cationicorganic polymer, anionic organic polymer, and the like, and combinationsthereof. A cationic inorganic polymer useful in the process ispolyaluminum chloride. Cationic inorganic molecules include thoseselected from the group consisting of aluminum sulfate, aluminumchloride, polyaluminum chloride, aluminum chlorohydrate, ferricchloride, ferric sulfate, ferrous sulfate and sodium aluminate and thelike, and combinations thereof. Cationic organic polymer useful in theinvention include polymers formed from the monomers diallyl dimethylammonium chloride, ethylene imine, comonomers of epichlorohydrin anddimethylamine, cationically-modified tannins, melamine formaldehyde, andthe like and combinations thereof. For example, the cationic organicpolymer may be polydimethyldiallylammonium chloride (poly(DADMAC)). Theanionic organic polymer may comprise polyacrylate.

Water-soluble synthetic polymer flocculants that can be used in theprocess comprise water-soluble anionic, cationic, nonionic polymers, andamphoteric polymers. For purpose of this disclosure, water-solublesynthetic polymer shall include copolymers and terpolymers, as well ashomopolymers. Typically the water-soluble synthetic polymer used has aMw of from about 500,000 to about 25,000,000, preferably from about750,000 to about 20,000,000, and more preferably from about 1,000,000 toabout 18,000,000. The water-soluble synthetic polymers may be linear,branched, or cross-linked. Persons of ordinary skill in these arts,after reading this disclosure, will appreciate that all ranges andvalues within these explicitly stated ranges are contemplated.

Nonionic polymers include polymers formed from one or more water-solubleethylenically unsaturated nonionic monomers, for instance acrylamide,methacrylamide, hydroxyethyl acrylate and N-vinylpyrrolidone, preferablyacrylamide. Nonionic polymers also include alkoxylated multifunctionalalcohols.

Cationic polymers are formed from one or more ethylenically unsaturatedcationic monomers optionally with one or more of the nonionic monomersmentioned previously. The cationic polymer may also be amphotericprovided that there are predominantly more cationic groups than anionicgroups. The cationic monomers include dialkylamino alkyl(meth)acrylates,dialkylamino alkyl(meth)acrylamides, and diallyl dimethyl ammoniumchloride, including acid addition and quaternary ammonium salts thereof.Typical cationic monomers include the methyl chloride quaternaryammonium salts of dimethylamino ethyl acrylate and dimethyl aminoethylmethacrylate. Of particular interest are the copolymer of acrylamidewith the methyl chloride quaternary ammonium salts of dimethylaminoethyl acrylate (ADAME); the copolymer of acrylamide and acrylamidopropyltrimethyl ammonium chloride (APTAC); and the copolymer of acrylamide andacryloyloxyethyl trimethyl ammonium chloride (AETAC); and the copolymerof epichlorohydrin and dimethylamine.

Anionic polymers are formed from one or more ethylenically unsaturatedanionic monomers or a blend of one or more anionic monomers with one ormore of the nonionic monomers mentioned previously. The anionic monomersinclude acrylic acid, methacrylic acid, maleic acid, crotonic acid,itaconic acid, vinyl sulfonic acid, allyl sulfonic acid,2-acrylamido-2-methylpropane sulfonic acid (AMPS), acrylamide, mixturesthereof, and salts thereof.

Of particular interest are copolymers and/or terpolymers of monomersselected from the group consisting of acrylamide, 2-acrylamido2-methylpropane sulfonic acid (AMPS), acrylic acid, and (meth)acrylicacid. For example, the anionic polymer may be selected from the groupconsisting of copolymers derived from 2-acrylamido 2-methylpropanesulfonic acid, copolymers of acrylic acid and acrylamide, homopolymersof acrylic acid, homopolymers of acrylamide, and combinations thereof.Typically used as anionic polymer are the copolymer of sodium acrylateand acrylamide and the copolymer of acrylic acid and acrylamide.

Also of particular interest are copolymers of AMPS and acrylamidewherein the mole percent of AMPS is from about 10 mole percent to about25 mole percent, and terpolymers of AMPS, acrylamide, and acrylic acidwherein the mole percent of AMPS is from about 10 mole percent to about30 mole percent, the mole percent of acrylamide is from about 40 molepercent to about 60 mole percent, and the mole percent of acrylic acidis from about 20 mole percent to about 40 mole percent. Otherwise,homopolymers of acrylic acid or copolymers of acrylic acid andacrylamide are of particular interest.

The water-soluble synthetic polymer can be prepared by polymerization ofa water soluble monomer or water soluble monomer blend according tomethods well known in the art. The water soluble monomers typically arewater soluble monomers or water soluble monomer blend having asolubility in water of at least 5 g in 100 ml of water.

Typically the rheology modifier is added to the aqueous dispersion priorto the water-soluble synthetic polymer flocculant. In an embodiment, theinvention concerns a process comprising the steps of a) adding aneffective amount of at least one rheology modifier selected from thegroup consisting of natural polymers, semi-natural polymers, syntheticmaterials and combinations thereof to an aqueous dispersion and b) thenin a separate step adding at least one water-soluble synthetic polymerflocculant selected from the group consisting of inorganic polymer,cationic inorganic molecule, cationic organic polymer, anionic organicpolymer and combinations thereof. The amount of rheology modifier andwater soluble synthetic polymer flocculant effective to promote lowerrheological properties such as yield stress or viscosity and accelerateflocculation, sedimentation and the dewatering process for effectivesolid/liquid separation will be dependent on the characteristicproperties of the selected rheology modifier and water-soluble syntheticpolymer flocculant, the morphology of the particles in the aqueousdispersion, and the concentration of the aqueous dispersion duringliquid-solid separation. The weight ratio of rheology modifier to watersoluble synthetic polymer flocculant is a ratio that effectively reducesthe yield stress of the aqueous dispersion, which generally is a ratiois from about 4:1 to about 1:4, and typically ranges from about 0.10:1.0to about 2.0:1.0, preferably from about 0.20:1.0 to about 1.0:1.0, andmore preferably from about 0.25:1.0 to about 0.75:1.0. The total amountof rheology modifier and water soluble synthetic polymer flocculant usedto treat the aqueous system varies over wide ranges but typically rangesfrom about 1.0 to about 1000 grams per metric ton of aqueous systemtreated, preferably from about 2.0 to about 800 grams per metric ton,and more preferably from about 10.0 to about 600 grams per metric ton.Persons of ordinary skill in these arts, after reading this disclosure,will appreciate that all ranges and values within these explicitlystated ranges are contemplated.

The total solids found in the aqueous dispersion can vary over wideranges, but typically ranges from about 25 g/liter to about 2,000g/liter, such as about 50 g/liter to about 2,000 g/liter. The process isparticularly useful in reducing the yield stress of the aqueousdispersion where the aspect ratio of the solids is less than about 1.0,more particularly when the aspect ratio is less than about 0.5, and/orthe solids if the aqueous dispersion contains a substantial amount ofgangue. Persons of ordinary skill in these arts, after reading thisdisclosure, will appreciate that all ranges and values within theseexplicitly stated ranges are contemplated.

In particular the method may be applied in a unit operation within in amining operation, such as for a liquid-solid separation unit, forexample a conventional clarifier or thickener vessel as a model piece ofequipment, although the process is applicable for any typicalliquid-solid separation unit operation. Regarding the order of addition,or sequence of treatment, the rheology modifiers were found to be mosteffective when applied to the aqueous dispersion prior to theapplication of the water-soluble synthetic polymer flocculant, asopposed to treating the substrate with both the rheology modifier andwater-soluble synthetic polymer flocculant simultaneously, or treatingthe substrate with the rheology modifier after the addition of thewater-soluble synthetic polymer flocculant. With respect to, forexample, conventional clarifier or thickener vessel or other type ofliquid-solid separation equipment the water-soluble synthetic polymerflocculant is typically used to treat the substrate, i.e. the aqueousdispersion, within the conventional clarifier or thickener vessel tofacilitate the concentration and dewatering of the aqueous dispersion ofthe substrate. Thus, in the processes of the invention the water-solublesynthetic polymer flocculant is preferably added into the center feedwell of the clarifier or thickener vessel where the substrate firstenters the clarifier or thickener vessel from the feed pipe. Thewater-soluble synthetic polymer flocculant may be fed through a portinto the feed pipe at a point close to the thickener vessel feed well ormay be fed at multiple points, i.e., into the feed well and through thefeed pipe at points close to the feed well. In these embodiments, therheology modifier is added into the feed pipe, or other unit operationleading to the feed pipe, prior to the introduction of the water-solublesynthetic polymer flocculant to the substrate in the conventionalclarifier or thickener vessels or other liquid-solid separationequipment or apparatus. The net effect of feeding the rheology modifierprior to the water-soluble synthetic polymer flocculant is to pre-treator condition the surface of the substrate before it interacts with theflocculant.

The rheology modifier may be applied in the absence of the water-solublesynthetic polymer flocculant in embodiments where the desired effectscan be achieved without the properties associated with the water solublesynthetic polymer flocculant, such as where dewatering is not an issue.For example, direct injection into a pipeline feed of concentratedslurry to reduce yield stress. In this embodiment, the process typicallycomprises the step of adding an effective amount of at least onerheology modifier to an aqueous dispersion. The rheology modifier inthis process is typically selected from the group consisting of naturalpolymers, semi-natural polymers, synthetic materials and combinationsthereof.

EXAMPLES

In the examples, unless otherwise noted, the reagents used in theexamples are those set forth in Table 1.

TABLE I Reagents Reagent Product Class Type Charge MW RangeFunctionality Full Product Trade Name Rheology Zalta ™ natural organicnon-ionic med MW poly- Ashland ZaltaTM VM1120 Modifier A VM1120saccharide Rheology Zalta ™ natural organic non-ionic med MW poly-Ashland ZaltaTM VM1122 Modifier B VM1122 saccharide Rheology USB naturalorganic non-ionic med MW poly- USB dextran 5-40M Modifier C dextran5-40M saccharide Rheology USB natural organic non-ionic low MW poly- USBdextan <15K Modifier D dextran <15K saccharide Rheology Ambergum ™ semi-organic anionic low MW carboxymethyl- Ashland Ambergum ™ 3021 Water-Modifier E 3021 natural cellulose Soluble Polymers Rheology Norlig Asemi- organic anionic low MW calcium Borregaard Norlig A CalciumModifier F natural lignosulfonate Lignosulfonate Rheology Carbose semi-organic anionic low MW carboxymethyl- Penn Carbose D-65 Modifier G D-65natural cellulose Rheology Carbose semi- organic anionic low MWcarboxymethyl- Penn Carbose LT-30 Modifier H LT-30 natural celluloseRheology Carbose semi- organic anionic low MW carboxymethyl- PennCarbose M-72 Modifier I M-72 natural cellulose Rheology N-Hance ™ semi-organic cationic low MW cationic Ashland N-Hance ™ 3196 Guar GumModifier J 3196 natural guar gum Rheology N-Hance ™ semi- organiccationic low MW cationic Ashland N-Hance ™ 3215 Cationic guar Modifier K3215 natural guar gum Rheology N-Hance ™ semi- organic cationic low MWcationic Ashland N-Hance ™ BF13 Cationic guar Modifier L BF13 naturalguar gum Rheology N-Hance ™ semi- organic cationic low MW cationicAshland N-Hance ™ BF17 Cationic Guar Modifier M BF17 natural guar gumDerivatives Rheology StaLok 400 semi- organic cationic med MW cationicTate & Lyle/A. E. Staley StaLok 400 Modifier W natural starch RheologyStaLok 410 semi- organic cationic med MW cationic Tate & Lyle/A. E.Staley StaLok 410 Modifier X natural starch Rheology StaLok 430 semi-organic cationic med MW cationic Tate & Lyle/A. E. Staley StaLok 430Modifier Y natural starch Rheology Good-Rite synthetic organic anioniclow MW polyacrylate B. F. Goodrich Good-Rite K-752 Modifier N K-752Rheology Praestol ™ synthetic organic cationic low MW coagulant AshlandPraestol ™ 187 K FLOCCULANT Modifier O 187 K Rheology Praestol ™synthetic organic cationic low MW coagulant Ashland Praestol ™ 193 KFLOCCULANT Modifier P 193 K Rheology Amersep ™ synthetic inorganiccationic low MW coagulant Ashland Amersep ™ 5320 NEUTRALIZING Modifier Q5320 AGENT Rheology Chargepac ™ synthetic inorganic cationic low MWcoagulant Ashland Chargepac ™ 6 COAGULANT Modifier R 6 RheologyChargepac ™ synthetic inorganic cationic low MW coagulant AshlandChargepac ™ 7 COAGULANT Modifier S 7 Rheology Chargepac ™ syntheticinorganic cationic low MW coagulant Ashland Chargepac ™ 10 COAGULANTModifier T 10 Rheology Chargepac ™ synthetic inorganic cationic low MWcoagulant Ashland Chargepac ™ 16 COAGULANT Modifier U 16 RheologyChargepac ™ synthetic inorganic cationic low MW coagulant AshlandChargepac ™ 60 COAGULANT Modifier V 60 Flocculant A Praestol ™ syntheticorganic anionic high MW anionic Ashland Praestol ™ 2530 FLOCCULANT 2530polyacrylamide Flocculant B Praestol ™ synthetic organic anionic high MWanionic Ashland Praestol ™ 2640 FLOCCULANT 2640 polyacrylamideFlocculant C Praestol ™ synthetic organic anionic high MW anionicAshland Praestol ™ A 4040 L A 4040 L polyacrylamide FLOCCULANTFlocculant D Praestol ™ synthetic organic anionic high MW anionicAshland Praestol ™ A 24587 A 24587 polyacrylamide Flocculant E FlopaamAL synthetic organic anionic high MW anionic SNF AL80EH 80 EHpolyacrylamide Flocculant F Flopaam AN synthetic organic anionic high MWanionic SNF Flopaam AN 113 SH 113 SH polyacrylamide

Unless otherwise indicated, the yield stress of the tested aqueousdispersion was determined by adding 1000 mL of an aqueous dispersion toa graduated cylinder, where first the rheology modifier(s) were added tothe aqueous dispersion, tamping the rheology modifier(s) into thedispersion three times with a plunger having perforated holes. Then, thewater-soluble synthetic polymer flocculant was added to the aqueousdispersion using the same mixing technique and number of tamps.

The rate at which the liquid-solid separation occurred was establishedby starting a timer at the point where the liquid-solid interfacereached the 1000 milliliter mark in the graduated cylinder and thenrecording the time at which the liquid-solid interface reached eachadditional 50 milliliters down to the 700 milliliter mark. Thesedimentation rate was calculated by subtracting the time recorded atthe 900 milliliter mark from the time recorded at the 700 millilitermark.

A compaction value was recorded after 18 hours. The subsequentmeasurements of yield stress were taken after the 24 hour mark. Toprepare the samples for analysis the liquid was siphoned out of the 1000milliliter graduated cylinders until there were only concentrated solidsleft in the cylinders. The resulting slurries were quantitativelytransferred into appropriately sized beakers. The slurries in thebeakers were allowed to rest for an additional 4 hours prior toconducting the yield stress measurements.

The yield stress (in Pa) was measured with a Brookfield HBDVIII Ultrarheometer or Brookfield RVDVIII Ultra rheometer using vane spindles. Thetested aqueous dispersion was placed in an appropriately sized beakerfor the vane spindle used. The selection of the spindle or rheometerdepended on the magnitude of range of yield stress measured. The vanespindle was lowered down into the aqueous dispersion to the vanespindle's primary mark. RHEOCALC® software was used to calculate theyield stress utilizing either the Bingham model or the Casson modelwhere noted.

Examples 1.II-D to 30.II-D

In Examples 1.II-D to 30.II-D, as set forth in Table II-D, gold ore feedconcentrate was treated with the rheology modifiers and water-solublesynthetic polymer flocculants set forth in Table II-D in the ratios anddosages set forth in the table. The treated aqueous dispersions wereanalyzed for sedimentation, compaction and change in yield stress inaccordance with the procedures set forth above. The properties andresults are set forth in Table II-D.

TABLE II-D Treatment of Gold Ore Filter Feed Concentrate Examples ofPresent Invention - Semi-natural Rheology Modifiers with SyntheticFlocculants Sedimen- Compac- Change Ratio Ratio Reagent Feed Pulp tationtion in Yield Exam- Re- Re- Re- Reagent Reagents 1 & 3 Dose SolidsDensity Rate 24 h Stress ples agent 1 agent 2 agent 3 2:Reagent 12:Reagent 3 (g/t) (%) (t/m3) (m/h) (mL) (from Blank) 1 Rheology N/AFlocculant F 0% 50% 128.9 15.5 1.1300 32 270  −8% Modifier E 2 RheologyN/A Flocculant F 0% 100%  128.9 15.5 1.1300 21 270 −16% Modifier E 3Rheology N/A Flocculant F 0% 75% 128.9 15.5 1.1300 28 270 −25% ModifierE 4 Rheology N/A Flocculant F 0% 50% 128.9 15.5 1.1300 17 270 −30%Modifier E 5 Rheology N/A Flocculant F 0% 100%  129.7 15.5 1.1231 23 285−39% Modifier E 6 Rheology N/A Flocculant F 0% 50% 129.7 15.5 1.1231 24280 −96% Modifier E 8 Rheology N/A Flocculant F 0% 100%  128.9 15.51.1300 22 290  −5% Modifier G 9 Rheology N/A Flocculant F 0% 50% 128.915.5 1.1300 25 275 −10% Modifier G 10 Rheology N/A Flocculant F 0% 100% 128.9 15.5 1.1300 23 290 −17% Modifier G 11 Rheology N/A Flocculant F 0%50% 129.7 15.5 1.1231 22 285 −39% Modifier G 12 Rheology N/A FlocculantF 0% 50% 129.7 15.5 1.1231 22 295 −41% Modifier G 13 Rheology N/AFlocculant F 0% 50% 129.7 15.5 1.1231 19 280  −3% Modifier H 14 RheologyN/A Flocculant F 0% 50% 129.7 15.5 1.1231 23 285 −67% Modifier H 15Rheology N/A Flocculant F 0% 50% 129.7 15.5 1.1231 21 285 −10% ModifierI 16 Rheology N/A Flocculant F 0% 100%  129.7 15.5 1.1231 23 300 −84%Modifier I 17 Rheology N/A Flocculant F 0% 100%  144.0 18.5 1.1291 15N/A  −4% Modifier K 18 Rheology N/A Flocculant F 0% 50% 112.8 17.81.1231 13 N/A −13% Modifier K 19 Rheology N/A Flocculant F 0% 25% 112.817.8 1.1231 13 N/A −19% Modifier K 20 Rheology N/A Flocculant F 0% 50%112.8 17.8 1.1231 15 N/A −20% Modifier K 21 Rheology N/A Flocculant F 0%50% 144.0 18.5 1.1291 12 N/A −21% Modifier K 22 Rheology N/A FlocculantF 0% 75% 112.8 17.8 1.1231 14 N/A −22% Modifier K 23 Rheology N/AFlocculant F 0% 75% 144.0 18.5 1.1291 17 N/A −23% Modifier K 24 RheologyN/A Flocculant F 0% 75% 112.8 17.8 1.1231 21 N/A −38% Modifier K 25Rheology N/A Flocculant F 0% 75% 112.8 17.8 1.1231 16 N/A −23% ModifierM 26 Rheology N/A Flocculant F 0% 75% 112.8 17.8 1.1231 16 N/A −31%Modifier M 27 Rheology N/A Flocculant F 0% 25% 112.8 17.8 1.1231 11 N/A−34% Modifier M 28 Rheology N/A Flocculant F 0% 50% 112.8 17.8 1.1231 18N/A −44% Modifier M 29 Rheology N/A Flocculant F 0% 100%  112.8 17.81.1231 20 N/A −44% Modifier M 30 Rheology N/A Flocculant F 0% 50% 112.817.8 1.1231 15 N/A −47% Modifier M

Examples 1.II-E to 16.II-E

In Examples 1.II-E to 16.II-E, as set forth in Table II-E, gold ore feedconcentrate was treated with the rheology modifiers and water-solublesynthetic polymer flocculants set forth in Table II-E in the ratios anddosages set forth in the table. The treated aqueous dispersions wereanalyzed for sedimentation, compaction and change in yield stress inaccordance with the procedures set forth above. The properties andresults are set forth in Table II-E.

TABLE II-E Treatment of Gold Ore Filter Feed Concentrate Examples ofPresent Invention - Synthetic Rheology Modifiers with SyntheticFlocculants Sedimen- Compac- Change Ratio Ratio Reagent Feed Pulp tationtion in Yield Exam- Re- Re- Re- Reagent Reagents 1 & 3 Dose SolidsDensity Rate 24 h Stress ples agent 1 agent 2 agent 3 2:Reagent 12:Reagent 3 (g/t) (%) (t/m3) (m/h) (mL) (from Blank) 1 Rheology N/AFlocculant F 0% 25% 110.5 18.2 1.1219 1 N/A  −6% Modifier Q 2 RheologyN/A Flocculant F 0% 50% 110.5 18.2 1.1219 2 N/A −47% Modifier Q 3Rheology N/A Flocculant F 0% 50% 110.5 18.2 1.1219 2 N/A  −8% Modifier T4 Rheology N/A Flocculant F 0% 50% 110.5 18.2 1.1219 3 N/A  −5% ModifierU 5 Rheology N/A Flocculant F 0% 25% 110.5 18.2 1.1219 3 N/A  −7%Modifier U 6 Rheology N/A Flocculant F 0% 50% 110.5 18.2 1.1219 2 N/A −6% Modifier R 7 Rheology N/A Flocculant F 0% 100%  110.5 18.2 1.1219 2N/A −19% Modifier R 8 Rheology N/A Flocculant F 0% 100%  110.5 18.21.1219 1 N/A −25% Modifier V 9 Rheology N/A Flocculant F 0% 100%  110.518.2 1.1219 2 N/A −17% Modifier S 10 Rheology N/A Flocculant F 0% 50%110.5 18.2 1.1219 2 N/A −19% Modifier S 11 Rheology N/A Flocculant F 0%25% 110.5 18.2 1.1219 2 N/A −42% Modifier S 12 Rheology N/A Flocculant F0% 100%  128.9 15.5 1.1300 27 260 −15% Modifier N 13 Rheology N/AFlocculant F 0% 75% 128.9 15.5 1.1300 27 260 −20% Modifier N 14 RheologyN/A Flocculant F 0% 50% 128.9 15.5 1.1300 21 270 −29% Modifier N 15Rheology N/A Flocculant F 0% 25% 110.5 18.2 1.1219 2 N/A  −3% Modifier O16 Rheology N/A Flocculant F 0% 25% 110.5 18.2 1.1219 1 N/A −10%Modifier P

Examples 1.II-F to 28.II-F

In Examples 1.II-F to 28.II-F, as set forth in Table II-F, gold ore feedconcentrate was treated with the rheology modifiers and water-solublesynthetic polymer flocculants set forth in Table II-F in the ratios anddosages set forth in the table. The treated aqueous dispersions wereanalyzed for sedimentation, compaction and change in yield stress inaccordance with the procedures set forth above. The properties andresults are set forth in Table II-F.

TABLE II-F Treatment of Gold Ore Filter Feed Concentrate Examples ofPresent Invention -Combinations of Natural and Semi-natural or SyntheticRheology Modifiers with Synthetic Flocculants Sedimen- Compac- ChangeRatio Ratio Reagent Feed Pulp tation tion in Yield Exam- Re- Re- Re-Reagent Reagents 1 & 3 Dose Solids Density Rate 24 h Stress ples agent 1agent 2 agent 3 2:Reagent 1 2:Reagent 3 (g/t) (%) (t/m3) (m/h) (mL)(from Blank) 1 Rheology Rheology Flocculant F 100% 50% 129.7 15.5 1.123127 280 −11% Modifier A Modifier E 2 Rheology Rheology Flocculant F 100%100%  129.7 15.5 1.1231 21 290 −86% Modifier A Modifier G 3 RheologyRheology Flocculant F 100% 50% 129.7 15.5 1.1231 27 280 −95% Modifier AModifier G 4 Rheology Rheology Flocculant F 100% 50% 129.7 15.5 1.123129 280 −50% Modifier A Modifier H 5 Rheology Rheology Flocculant F 100%100%  129.7 15.5 1.1231 21 285 −64% Modifier A Modifier H 6 RheologyRheology Flocculant F 100% 50% 129.7 15.5 1.1231 21 285 −75% Modifier AModifier H 7 Rheology Rheology Flocculant F 100% 50% 129.7 15.5 1.123120 285 −95% Modifier A Modifier I 8 Rheology Rheology Flocculant F 100%100%  129.7 15.5 1.1231 18 300 −100%  Modifier A Modifier I 9 RheologyRheology Flocculant F 100% 25% 112.8 17.8 1.1231 11 N/A  −7% Modifier AModifier K 10 Rheology Rheology Flocculant F 100% 75% 113.2 17.6 1.127113 N/A −16% Modifier A Modifier K 11 Rheology Rheology Flocculant F 100%75% 113.2 17.6 1.1271 9 N/A −18% Modifier A Modifier K 12 RheologyRheology Flocculant F 100% 50% 113.2 17.6 1.1271 13 N/A −19% Modifier AModifier K 13 Rheology Rheology Flocculant F 100% 50% 112.8 17.8 1.123121 N/A −24% Modifier A Modifier K 14 Rheology Rheology Flocculant F 100%50% 112.8 17.8 11231 6 N/A −25% Modifier A Modifier K 15 RheologyRheology Flocculant F 100% 100%  112.8 17.8 1.1231 19 N/A −28% ModifierA Modifier K 16 Rheology Rheology Flocculant F 100% 75% 112.8 17.81.1231 13 N/A −29% Modifier A Modifier K 17 Rheology Rheology FlocculantF 100% 100%  113.2 17.6 1.1271 15 N/A  −5% Modifier A Modifier L 18Rheology Rheology Flocculant F 100% 50% 113.2 17.6 1.1271 11 N/A  −9%Modifier A Modifier L 19 Rheology Rheology Flocculant F 100% 50% 113.217.6 1.1271 11 N/A −12% Modifier A Modifier L 20 Rheology RheologyFlocculant F 100% 100%  112.8 17.8 1.1231 17 N/A  −3% Modifier AModifier M 21 Rheology Rheology Flocculant F 100% 75% 113.2 17.6 1.127116 N/A  −3% Modifier A Modifier M 22 Rheology Rheology Flocculant F 100%100%  113.2 17.6 1.1271 15 N/A −14% Modifier A Modifier M 23 RheologyRheology Flocculant F 100% 75% 112.8 17.8 1.1231 21 N/A −15% Modifier AModifier M 24 Rheology Rheology Flocculant F 100% 25% 112.8 17.8 1.123111 N/A −29% Modifier A Modifier M 25 Rheology Rheology Flocculant F 100%100%  144.0 18.5 1.1291 13 N/A −12% Modifier A Modifier Q 26 RheologyRheology Flocculant F 100% 50% 144.0 18.5 1.1291 17 N/A −14% Modifier AModifier Q 27 Rheology Rheology Flocculant F 100% 75% 144.0 18.5 1.129112 N/A −22% Modifier A Modifier Q 28 Rheology Rheology Flocculant F 100%75% 144.0 18.5 1.1291 14 N/A  −4% Modifier A Modifier S

Examples 1.II-G to 4.II-G

In Examples 1.II-G to 4.II-G, as set forth in Table II-G, gold ore feedconcentrate was treated with the rheology modifiers and water-solublesynthetic polymer flocculants set forth in Table II-G in the ratios anddosages set forth in the table. The treated aqueous dispersions wereanalyzed for sedimentation, compaction and change in yield stress inaccordance with the procedures set forth above. The properties andresults are set forth in Table II-G.

TABLE II-G Treatment of Gold Ore Filter Feed Concentrate Examples ofPresent Invention - Combinations of Semi-natural and Synthetic RheologyModifiers with Synthetic Flocculants Sedimen- Compac- Change Ratio RatioReagent Feed Pulp tation tion in Yield Exam- Re- Re- Re- ReagentReagents 1 & 3 Dose Solids Density Rate 24 h Stress ples agent 1 agent 2agent 3 2:Reagent 1 2:Reagent 3 (g/t) (%) (t/m3) (m/h) (mL) (from Blank)1 Rheology Rheology Flocculant F 100% 75% 144.0 18.5 1.1291 12 N/A −6%Modifier K Modifier Q 2 Rheology Rheology Flocculant F 100% 100%  144.018.5 1.1291 14 N/A −21%  Modifier K Modifier Q 3 Rheology RheologyFlocculant F 100% 75% 144.0 18.5 1.1291 9 N/A −7% Modifier K Modifier S4 Rheology Rheology Flocculant F 100% 50% 144.0 18.5 1.1291 15 N/A −4%Modifier K Modifier V

Examples 1.III-C to 7.III-C

In Examples 1.III-C to 7.III-C, as set forth in Table III-C, phosphateore slurry was treated with the rheology modifiers and water-solublesynthetic polymer flocculants set forth in Table III-C in the ratios anddosages set forth in the table. The treated aqueous dispersions wereanalyzed for sedimentation, compaction and change in yield stress inaccordance with the procedures set forth above. The properties andresults are set forth in Table III-C.

Examples 1.III-D to 32.III-D

In Examples 1.III-D to 32.III-D, as set forth in Table III-D, phosphateore slurry was treated with the rheology modifiers and water-solublesynthetic polymer flocculants set forth in Table III-D in the ratios anddosages set forth in the table. The treated aqueous dispersions wereanalyzed for sedimentation, compaction and change in yield stress inaccordance with the procedures set forth above. The properties andresults are set forth in Table III-D.

Examples 1.III-E to 7.III-E

In Examples 1.III-E to 32.III-E, as set forth in Table III-E, phosphateore slurry was treated with the rheology modifiers and water-solublesynthetic polymer flocculants set forth in Table III-E in the ratios anddosages set forth in the table. The treated aqueous dispersions wereanalyzed for sedimentation, compaction and change in yield stress inaccordance with the procedures set forth above. The properties andresults are set forth in Table III-E.

TABLE III-C Treatment of Phosphate Ore Slurry Examples of PresentInvention - Semi-natural Rheology Modifiers with Synthetic FlocculantsSedimen- Compac- Change Ratio Ratio Reagent Feed Pulp tation tion inYield Exam- Re- Re- Re- Reagent Reagents 1 & 3 Dose Solids Density Rate24 h Stress ples agent 1 agent 2 agent 3 2:Reagent 1 2:Reagent 3 (g/t)(%) (t/m3) (m/h) (mL) (from Blank) 1 N/A Rheology Flocculant B N/A 75%10.9 20.3 1.1266 21.2 N/A −10% Modifier J 2 N/A Rheology Flocculant BN/A 25% 10.9 20.3 1.1266 18.7 N/A −31% Modifier J 3 N/A RheologyFlocculant B N/A 50% 12.3 18.4 1.1120 17.4 N/A  −1% Modifier K 4 N/ARheology Flocculant B N/A 75% 12.3 18.4 1.1120 15.9 N/A −18% Modifier K5 N/A Rheology Flocculant B N/A 75% 14.5 15.8 1.0862 17.6 N/A −21%Modifier L 6 N/A Rheology Flocculant B N/A 25% 14.0 16.2 1.0963 14.8 N/A −5% Modifier M 7 N/A Rheology Flocculant B N/A 50% 14.0 16.2 1.096317.6 N/A  −6% Modifier M

TABLE III-D Treatment of Phosphate Ore Slurry Examples of PresentInvention - Combinations of Natural and Semi-natural Rheology Modifierswith Synthetic Flocculants Sedimen- Compac- Change Ratio Ratio ReagentFeed Pulp tation tion in Yield Exam- Re- Re- Re- Reagent Reagents 1 & 3Dose Solids Density Rate 24 h Stress ples agent 1 agent 2 agent 32:Reagent 1 2:Reagent 3 (g/t) (%) (t/m3) (m/h) (mL) (from Blank) 1Rheology Rheology Flocculant F 100% 100%  54.0 10.5 1.9800 N/A N/A −5%Modifier A Modifier K 2 Rheology Rheology Flocculant F 100% 50% 54.010.5 1.9800 N/A N/A −9% Modifier A Modifier K 3 Rheology RheologyFlocculant F 100% 75% 50.6 19.5 1.1405 15.9 220 −12%  Modifier AModifier K 4 Rheology Rheology Flocculant F 100% 150%  50.6 19.5 1.140542.4 210 −40%  Modifier A Modifier L 5 Rheology Rheology Flocculant F100% 75% 50.6 19.5 1.1405 22.6 220 −65%  Modifier A Modifier L 6Rheology Rheology Flocculant F 100% 75% 50.6 19.5 1.1405 17.6 210 −23% Modifier A Modifier M 7 Rheology Rheology Flocculant C 200% 30% 50.511.7 1.0563 N/A 210 −1% Modifier A Modifier M 8 Rheology RheologyFlocculant C 400% 25% 50.5 11.7 1.0563 N/A 220 −3% Modifier A Modifier M9 Rheology Rheology Flocculant B 317% 50% 10.9 20.3 1.1266 23.4 N/A −2%Modifier A Modifier J 10 Rheology Rheology Flocculant B 295% 75% 10.920.3 1.1266 20.2 N/A −5% Modifier A Modifier J 11 Rheology RheologyFlocculant B 100% 50% 10.9 20.3 1.1266 27.4 N/A −6% Modifier A ModifierJ 12 Rheology Rheology Flocculant B  32% 25% 10.9 20.3 1.1266 21.2 N/A−10%  Modifier A Modifier J 13 Rheology Rheology Flocculant B 317% 25%10.9 20.3 1.1266 21.2 N/A −15%  Modifier A Modifier J 14 RheologyRheology Flocculant B  32% 25% 10.9 20.3 1.1266 13.2 N/A −17%  ModifierA Modifier J 15 Rheology Rheology Flocculant B  32% 50% 12.3 18.4 1.112021.0 N/A −9% Modifier A Modifier K 16 Rheology Rheology Flocculant B N/A25% 14.0 16.2 1.0963 20.9 N/A  0% Modifier A Modifier M 17 RheologyRheology Flocculant B 295% 75% 14.0 16.2 1.0963 17.6 N/A −1% Modifier AModifier M 18 Rheology Rheology Flocculant B 100% 25% 14.0 16.2 1.096313.8 N/A −2% Modifier A Modifier M 19 Rheology Rheology Flocculant B 34% 75% 14.0 16.2 1.0963 21.2 N/A −2% Modifier A Modifier M 20 RheologyRheology Flocculant B 317% 50% 14.0 16.2 1.0963 21.2 N/A −10%  ModifierA Modifier M 21 Rheology Rheology Flocculant B  32% 25% 14.0 16.2 1.096316.7 N/A −11%  Modifier A Modifier M 22 Rheology Rheology Flocculant B100% 50% 14.0 16.2 1.0963 21.2 N/A −12%  Modifier A Modifier M 23Rheology Rheology Flocculant B 317% 25% 14.0 16.2 1.0963 14.3 N/A −14% Modifier A Modifier M 24 Rheology Rheology Flocculant B 100% 76% 14.016.2 1.0963 15.9 N/A −14%  Modifier A Modifier M 25 Rheology RheologyFlocculant B 100% 25% 14.0 16.2 1.0963 12.4 N/A −17%  Modifier AModifier M 26 Rheology Rheology Flocculant B 317% 25% 14.0 16.2 1.096317.6 N/A −27%  Modifier A Modifier M 27 Rheology Rheology Flocculant B 50% 19% 80.8 11.7 1.0563 N/A 220 −5% Modifier A Modifier W 28 RheologyRheology Flocculant B 100% 25% 80.8 11.7 1.0563 N/A 230 −10%  Modifier AModifier W 29 Rheology Rheology Flocculant B  50% 19% 80.8 11.7 1.0563N/A 210 −9% Modifier A Modifier X 30 Rheology Rheology Flocculant B 100%25% 80.8 11.7 1.0563 N/A 205 −16%  Modifier A Modifier X 31 RheologyRheology Flocculant B  50% 19% 80.8 11.7 1.0563 N/A 240  0% Modifier AModifier Y 32 Rheology Rheology Flocculant B 100% 25% 80.8 11.7 1.0563N/A 265 −11%  Modifier A Modifier Y

TABLE III-E Treatment of Phosphate Ore Slurry Examples of PresentInvention - Combinations of Semi-natural and Natural Rheology Modifierswith Synthetic Flocculants Sedimen- Compac- Change Ratio Ratio ReagentFeed Pulp tation tion in Yield Exam- Re- Re- Re- Reagent Reagents 1 & 3Dose Solids Density Rate 24 h Stress ples agent 1 agent 2 agent 32:Reagent 1 2:Reagent 3 (g/t) (%) (t/m3) (m/h) (mL) (from Blank)Rheology N/A Flocculant C  0% 25% 146.3 4.3 1.0055 N/A 100  −9% ModifierF Rheology Rheology Flocculant C 200% 30% 146.3 4.3 1.0055 N/A 90 −12%Modifier F Modifier A Rheology Rheology Flocculant C 200% 60% 146.3 4.31.0055 N/A 100 −21% Modifier F Modifier A Rheology Rheology Flocculant C400% 25% 146.3 4.3 1.0055 N/A 90 −22% Modifier F Modifier A RheologyRheology Flocculant C 100% 40% 146.3 4.3 1.0055 N/A 90 −35% Modifier FModifier A Rheology Rheology Flocculant C 200% 30% 50.5 11.7 1.0563 N/A185  −3% Modifier M Modifier A Rheology Rheology Flocculant C 400% 25%50.5 11.7 1.0563 N/A 190  −5% Modifier M Modifier A

Examples 1.IV to 10.IV

In Examples 1.IV to 10.IV, as set forth in Table IV, bauxite residualswere treated with the rheology modifiers and water-soluble syntheticpolymer flocculants set forth in Table IV in the ratios and dosages setforth in the table. The treated aqueous dispersions were analyzed forsedimentation, compaction and change in yield stress in accordance withthe procedures set forth above. The properties and results are set forthin Table IV.

TABLE IV Treatment of Bauxite Residuals Sedimen- Compac- Change RatioRatio Reagent Feed Pulp tation tion in Yield Exam- Re- Re- Re- ReagentReagents 1 & 3 Dose Solids Density Rate 24 h Stress ples agent 1 agent 2agent 3 2:Reagent 1 2:Reagent 3 (g/t) (%) (t/m3) (m/h) (mL) (from Blank)1 Rheology Rheology Flocculant E 500% 50% 20.6 35.4 1.37 16 160 −68%Modifier D Modifier C 2 Rheology Rheology Flocculant E 500% 50% 20.635.4 1.37 10 155 −78% Modifier D Modifier A 3 Rheology RheologyFlocculant E 500% 50% 20.6 35.4 1.37 21 165 −91% Modifier A Modifier C 4Rheology Rheology Flocculant E  33% 100%  10.3 35.4 1.37 26 180 −11%Modifier A Modifier K 5 Rheology Rheology Flocculant E 300% 50% 20.635.4 1.37 20 155 −51% Modifier A Modifier K 6 Rheology RheologyFlocculant E 1100%  50% 20.6 35.4 1.37 18 170 −57% Modifier A Modifier K7 Rheology Rheology Flocculant E 500% 50% 20.6 35.4 1.37 18 155 −57%Modifier A Modifier K 8 Rheology Rheology Flocculant E 1100%  50% 20.635.4 1.37 28 165 −57% Modifier A Modifier K 9 Rheology RheologyFlocculant E 500% 50% 20.6 35.4 1.37 28 165 −59% Modifier A Modifier K10 Rheology Rheology Flocculant E 300% 50% 20.6 35.4 1.37 17 165 −69%Modifier A Modifier K

Examples 1.V to 10.V

In Examples 1.V to 10.V, as set forth in Table V, copper tailings weretreated with the rheology modifiers and water soluble synthetic polymerflocculants set forth in Table V in the ratios and dosages set forth inthe table. The treated aqueous dispersions were analyzed forsedimentation, compaction and change in yield stress in accordance withthe procedures set forth above. The properties and results are set forthin Table V.

TABLE V Treatment of Copper Tailings Sedimen- Compac- Change Ratio RatioReagent Feed Pulp tation tion in Yield Exam- Re- Re- Re- Reagent Reagent1 & 3 Dose Solids Density Rate 24 h Stress ples agent 1 agent 2 agent 32:Reagent 1 2:Reagent 3 (g/t) (%) (t/m3) (m/h) (mL) (from Blank) A N/AN/A Flocculant B N/A 27.8 12.7 1.067 10 218  0% B Rheology N/AFlocculant B  0% 25% 29.5 12.0 1.060 14 200  1% Modifier A 1 RheologyRheology Flocculant B 100%  51% 26.9 12.9 1.080 N/A 210 −4% Modifier AModifier K 2 Rheology Rheology Flocculant B 100%  25% 26.9 12.9 1.080 47210 −5% Modifier A Modifier K 3 Rheology Rheology Flocculant B 280%  25%30.1 11.8 1.061 14 210 −4% Modifier A Modifier M 4 Rheology RheologyFlocculant B 34% 50% 30.1 11.8 1.061 10 220 −5% Modifier A Modifier M 5Rheology Rheology Flocculant B 280%  25% 25.4 13.7 1.074 14 225 −5%Modifier A Modifier W 6 Rheology Rheology Flocculant B 100%  51% 26.213.4 1.072 11 245 −2% Modifier A Modifier X 7 Rheology RheologyFlocculant B 280%  25% 26.2 13.4 1.072  9 225 −3% Modifier A Modifier X8 Rheology Rheology Flocculant B 36% 25% 26.2 13.4 1.072 11 235 −3%Modifier A Modifier X 9 Rheology Rheology Flocculant B 34% 50% 26.2 13.41.072 13 240 −6% Modifier A Modifier X 10  Rheology Rheology FlocculantB 33% 75% 26.2 13.4 1.072 10 245 −9% Modifier A Modifier X

Example 33

DREWFLOC® 270 and ZALTA VM 1122, both from Ashland, were added to goldore slurry in ratios of ZALTA VM 1122 to DREWFLOC 270 of 1:1, 2:1, 3:1and 4:1. This was dosed into separate slurries in amounts of 54grams/ton of slurry (0.12 pounds/ton), 82 grams/ton of slurry (0.18pounds/ton) and 109 grams/ton of slurry (0.24 pounds/ton). Yieldstresses were measured for each slurry as well as controls (no naturalpolymer used). The results are set forth in Table VI.

TABLE VI Yield Stress (dyne/cm²) Ratio of Natural Polymer Dosage (g/tonof slurry) to Flocculant 54 82 109 Control (0) 1474 2281 2662 1:1 11562588 3140 2:1 1936 2393 2672 3:1 1721 2343 2295 4:1 2263 2547 2944

The slurry dosed at 54 grams/ton of slurry showed reduction in yieldstress compared to the control at a ratio of 1:1. The slurry dosed at109 grams/ton of slurry showed decrease in yield stress at a ratio of3:1.

Compaction (solids content) was measured for each slurry as well ascontrols (no natural polymer used). The results are set forth in TableVII.

TABLE VII Compaction (% Solids) Ratio of Natural Polymer Dosage(grams/ton of slurry) to Flocculant 54 82 109 Control (0) 48.68 48.0448.89 1:1 48.38 48.78 48.89 2:1 48.38 48.16 49.23 3:1 47.88 48.62 51.674:1 47.76 48.76 48.88

With dosage at 109 grams/ton of slurry, there was increase incompaction, solids content, with a peak at the ratio of 3:1, whichcorrelates with the peak reduction in yield stress for this dosage atthe 3:1 ratio. It is noted, however, that application of the rheologymodifier and flocculant will be process and process condition dependentin that the higher solids in the evaluated gold ore process shifted thetotal dosage to the higher levels to achieve optimal efficacy, whereaslower feed solids may shift the total dosage requirements to achievehigher efficacy in rheology and increase in compaction to a loweroverall dosage.

We claim:
 1. A process for reducing the yield stress of a mineral slurrycomprising adding to the mineral slurry a rheology modifier followed byadding at least one water-soluble synthetic polymer flocculant; whereinthe rheology modifier is a natural polymer; wherein the weight ratio ofthe rheology modifier to flocculant is from about 4:1 to about 1:4 andthe total amount of rheology modifier and flocculant is from about 1.0to about 1,000 grams per metric ton of mineral slurry treated; andwherein the total solids of the aqueous dispersion prior to addition ofthe rheology modifier and flocculant is from about 25 q/liter to about2,000 q/liter; wherein the natural polymer is a polysaccharide; andwherein the rheology modifier and flocculant are added in an amounteffective to reduce the yield stress of the mineral slurry by at least25%.
 2. A process for improving the rheological properties of a mineralslurry comprising (a) adding at least one rheology modifier to themineral slurry, wherein the rheology modifier is a natural polymerhaving a molecular weight of from about 5,000 to about 40,000,000; and(b) then adding at least one water-soluble synthetic polymer flocculanthaving a weight average molecular weight of from about 500,000 to about25,000,000 to the mineral slurry, and wherein the water-solublesynthetic polymer flocculant is selected from the group consisting ofwater-soluble anionic polymer, cationic polymer, amphoteric polymer,nonionic polymer, and combinations thereof; wherein the weight ratio ofthe rheology modifier to flocculant is from about 4:1 to about 1:4 andthe total amount of rheology modifier and flocculant is from about 1.0to about 1,000 grams per metric ton of mineral slurry treated; andwherein the total solids of the mineral slurry prior to addition of therheology modifier and flocculant is from about 25 g/liter to about 2,000g/liter; wherein the natural polymer is a polysaccharide; wherein themineral slurry comprises a mineral selected from the group consisting ofgold, phosphate, silver, platinum, copper, nickel, zinc, lead,molybdenum, iron, coal and aluminum; and wherein the yield stress of themineral slurry is reduced by at least 25%.
 3. The process of claim 1wherein the polysaccharide is selected from the group consisting ofpotato starch, xanthan gum, guar, dextran, cellulose derivatives andglycosaminoglycan.
 4. The process of claim 2 wherein the syntheticpolymer flocculant is an anionic polymer comprising polyacrylate.
 5. Theprocess of claim 2 wherein the anionic polymer comprises a monomerselected from the group consisting of acrylic acid, methacrylic acid,maleic acid, crotonic acid, itaconic acid, vinyl sulfonic acid, allylsulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, acrylamideand salts thereof.
 6. The process of claim 2 wherein the flocculant is acationic polymer comprising a monomer selected from the group consistingof dialkylamino alkyl (meth) acrylate, acid addition salts ofdialkylamino alkyl (meth) acrylate, quaternary ammonium salts ofdialkylamino alkyl (meth) acrylate, dialkylamino alkyl (meth)acrylamide, acid addition salts of dialkylamino alkyl (meth) acrylamide,quaternary ammonium salts of dialkylamino alkyl (meth) acrylamide,diallyl dimethyl ammonium chloride, acid addition salts of diallyldimethyl ammonium chloride and quaternary ammonium salts of diallyldimethyl ammonium chloride.
 7. The process of claim 2 wherein theflocculant is a nonionic polymer comprising a monomer selected from thegroup consisting of acrylamide, methacrylamide, hydroxyethyl acrylateand N-vinylpyrrolidone.